no premanent 4x4 should be towed any great distance - recovery is Ok but much further leads to massive problems
If you want to tow a Defender et al you'll need to remove the rear drive shaft at least and both boxes in neutral.
Interesting, Land Rover's own advice (and the way we have always done it on Military and civilian vehicles) is to tow with both boxes in neutral and diff locks released - all you are doing is turning the box output shafts. There's no wind-up and there should be no problems.
If the front is lifted it is recommended that you remove the front prop shaft or, for short recoveries, allow the front wheels to spin with the diff lock engaged.
We have never had problems with these methods.